Channel quality indicator for a communication system

ABSTRACT

A method and apparatus for generating a performance indicator in a high-speed communication system. A plurality of disparate communication status signals with differing formats from a transceiver are combined in a logic module to create a single link quality indicator signal. The link quality indicator signal is used to encode different operational states of the transceiver from fully operational, to marginally operational, to failed. The link quality indicator signal is advantageously employed to drive a LED creating a visual performance indicator.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.12/710,929, Feb. 23, 2010, which is a continuation of U.S. patentapplication Ser. No. 11/332,937, filed Jan. 17, 2006, now U.S. Pat. No.7,668,108, which is a continuation of U.S. patent application Ser. No.09/841,588, filed Apr. 23, 2001, now U.S. Pat. No. 6,987,737, whichclaims the priority of U.S. Provisional Patent Application No.60/198,836, filed Apr. 21, 2000. All of the above-referencedapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to networked systems and morespecifically to performance indicators in a high-speed communicationsystem.

High-speed network devices within high-speed communication systems mayemploy disparate communication modules with each communication modulehandling a separate function for the high-speed communications device.Each communication module may generate a variety of status signalsrelated to the communication module's internal processes. These statussignals may relate to the quality of the communication link establishedby the high-speed communications device. For example, a communicationmodule may have an internal process for handling an auto-negotiationprocess, such as the auto-negotiation process defined in the well knownIEEE 802.3 network standard as employed by Broadcom Inc.'s BCM5400100/1000BASE-T Gigabit Ethernet Transceiver, in which case thecommunication module may provide status signals indicating the progressof the auto-negotiation process.

A high-speed communications device may comprise a number ofcommunication modules with each module generating its own statussignals. The format of the status signals may vary in characteristicsdependent on the nature of a variable value encoded within the statussignal. For example, some of the signals may be binary in nature,indicating either total failure or normal operation, while other signalsmay encode quantitative information, such as number of communicationerrors per unit of time.

Each communication module may generate its own status signals indicatingthat the communication module is functioning normally independently of acommunication module that may be experiencing processing errors. In thiscase, monitoring a single status signal or a set of status signals froma communication module may not indicate the quality of the communicationlink established by the high-speed communications device.

Therefore, a need exists for a method for generating a high-speedcommunication system performance signal incorporating a variety ofcommunication status signals. The present invention meets such need.

SUMMARY OF THE INVENTION

In one aspect of the current invention, an apparatus comprising aquality indicator logic module receives a set of communication statussignals from a transceiver in a high-speed communications network. Thequality indicator logic module generates a link quality indicator signalbased on the set of communication status signals.

In another aspect of the current invention, the link quality indicatorsignal is used to drive a Light Emitting Diode (LED) creating a visualdisplay.

In another aspect of the invention, a quality indicator process isprovided for generating a link quality indicator signal using anauto-negotiation status signal, a link status signal, a local receiverstatus signal, a receive error status signal, and a MSE communicationstatus signal.

At reset, the quality indicator process generates a link qualityindicator signal at a first signal level.

The quality indicator process then sets the link quality indicatorsignal to a second signal level if the auto-negotiation complete statussignal indicates a local transceiver auto-negotiation process iscomplete. If the auto-negotiation process is not complete, the qualityindicator process sets the link quality indicator signal to the firstsignal level and continues processing by checking the auto-negotiationcomplete status signal again.

The quality indicator process checks the link status signal and returnsto checking the auto-negotiation complete status signal if the linkstatus signal indicates that a network channel has not been established.

The quality indicator process checks the local receiver communicationstatus signal and sets the link quality indicator signal at the firstsignal level and continues checking the link status if a local receiverstatus signal indicates that the local transceiver is not functional.

The quality indicator process then sets the link quality indicatorsignal at the second signal level if the local receiver status signalindicates that the local transceiver is functional.

The quality indicator process then sets the link quality indicatorsignal at the first signal level for a first period of time and thensets the link quality indicator signal at the second signal level forthe same period of time if a receive error status signal indicates thatthe local transceiver has a reception error.

The quality indicator process sets the link quality indicator signal atthe first signal level for a second period of time and sets the linkquality indicator signal at the second signal level for the same periodof time if the MSE status signal indicates that a MSE of the localtransceiver exceeds a SNR threshold status signal level.

The quality indicator process repeats the process starting with checkingthe link status signal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription and accompanying drawings wherein:

FIG. 1 is a block diagram depicting an embodiment of a performanceindicator according to the present invention;

FIG. 2 is a block diagram depicting an LED embodiment of a performanceindicator according to the present invention; and

FIG. 3 is a process flow diagram of an embodiment of a performanceindicator according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram depicting an embodiment of a performanceindicator according to the present invention. A local network chip 10 isoperably coupled through a computer network 30 to a remote networkdevice 20 resulting in a high speed communication system 22. The localnetwork chip and the remote network device communicate with each otherover the network using the known IEEE 802.3 networking standard creatinga network channel 32 through the network. A single performance indicatorsignal, herein termed a link quality indicator signal, 40 is generatedby the local network chip to indicate the quality of the networkchannel. In operation, the local network chip monitors the quality ofthe network channel and changes the level of the link quality indicatorsignal based on the quality of the network channel.

The local network chip includes a local transceiver 50 operably coupledvia a plurality of network channel status signals 53 to a qualityindicator logic module 60. The quality indicator logic module includesan encoded process 62 for receiving the plurality of network channelstatus signals transmitted by the local transceiver and processing theplurality of received network channel status signals to generate asingle link quality indicator signal. The quality indicator logic module60 generates a link quality indicator signal including a plurality ofpossible timing sequences 70. Each of the timing sequences encodes adifferent aspect of the quality of the network channel.

In one embodiment of a link quality indicator according to the presentinvention, aperiodic link quality indicator signals are generated toindicate either that the network link is fully operational or that thenetwork link has completely failed.

In another embodiment of a link quality indicator according to thepresent invention, a plurality of periodic link quality indicatorsignals are generated with the period of the generated link qualityindicator signal indicating a different problem within the local networkchip's communication modules.

The local transceiver includes a plurality of operably coupledcommunication modules 52 that generate and control signals used toestablish the network channel. The communication modules generate statussignals including the plurality of network channel status signalstransmitted by the local transceiver to the quality indicator logicmodule. These network channel status signals are generated according tothe known IEEE 802.3 networking standard. The network channel statussignals may or may not share the same format. For example, some of thesignals may be binary in nature, indicating either total failure ornormal operation, while other signals may encode quantitativeinformation, such as number of errors per unit of time.

In an embodiment of a local network chip according to the presentinvention, the local transceiver includes communication modules 52. Thecommunication modules include higher level logic for controlling thetransceiver operations as well as signal processing circuitry and signalprocessing logic responsive to the higher level logic (for example, thePHY module) for controlling the operations of the signal processingcircuitry.

The communication modules further include logic for auto-negotiation ofa master/slave relationship according to the IEEE 802.3 standard. Thecommunication modules generate an auto-negotiation complete signal 76(for example, the flp_link_good signal as defined in the IEEE 802.3standard) indicating that the communication modules have completed anattempted auto-negotiation with the remote network device according tothe IEEE 802.3 standard.

Even though the auto-negotiation sequence is completed, the link may nothave been established. The communication modules include logic forgenerating a link status signal 76 according to the IEEE 802.3networking standard at the end of the auto-negotiation sequenceindicating whether or not a network link has been properly established.

The communication modules further include logic for generating a Signalto Noise Ratio (SNR) threshold value signal 78 that correlates with thea maximum Bit Error Rate (BER) as provided for in the IEEE 802.3networking standard. The SNR threshold is programmable by an externalcontrol program (not shown) thus facilitating the integration of thelocal network chip in a larger network device.

In an embodiment of a quality indicator according to the presentinvention, the SNR threshold is set slightly higher than the SNRthreshold called for in the IEEE 802.3 networking standard.

The communication modules generate a local receiver status signal 80 asprovided for in the IEEE 802.3 networking standard. The local receiverstatus signal depends on a SNR as determined by the signal processingcircuitry and on the state of a descrambler circuit included in thesignal processing circuitry. If the SNR is low and the descramblercircuit can no longer decode the received signals, the signal processinglogic sets the local receiver status signal to indicate that data can nolonger be sent reliably over the network channel.

The communication modules further include control logic for generating aMSE signal 82 proportional to the Mean Square Error (MSE) produced bythe signal processing circuitry. The MSE signal correlates with the SNRof the signal processing circuitry.

The s communication modules further include control logic for generatinga receive error signal 84. The receive error signal is a combination ofa false carrier sense signal as provided for in the IEEE 802.3networking standard and a receive coding error as provided for in theIEEE 802.3 networking standard. The false carrier sense signal indicatesif the local transceiver receives a frame that does not conform to theIEEE 802.3 networking standard. The receive coding error signalindicates if a frame contains a packet with an error such as a prematurepacket end as provided for in the IEEE 802.3 networking standard.

The quality indicator logic receives a clocking signal 72 from the localnetwork chip's timing circuit. The clocking signal is used to providetiming information for the quality indicator logic module to generate aplurality of link quality indicator signals with various timingcharacteristics.

The quality indicator logic module receives the previously describednetwork channel status signals and generates a single link qualityindicator signal including a plurality of possible timing sequences 70.Each of the timing sequences encodes a different aspect of the qualityof the network channel.

If the quality indicator logic module determines that the network linkis functioning normally, the link quality indicator signal is driven lowand remains low as long as the network link is functioning normally 86.This creates a first aperiodic link quality indicator signal indicatingthat the network link is fully operational.

If the local network chip is unable to establish and maintain a networkchannel with the remote network device, then the link quality indicatorsignal is driven high 88 and it remains in that state until the localnetwork chip can reestablish the network channel. This creates a secondaperiodic link quality indicator signal indicating that the network linkis not operational at all.

If the local network chip detects a false carrier sense signal or areceive coding error signal, the link quality indicator signal is drivenhigh then low at a low frequency 92. This creates a first periodic linkquality indicator signal indicating that the network link is marginallyoperational because there are framing or receive coding errors.

If the local network chip detects that the MSE is greater than the SNRthreshold value, then the link quality indicator signal is driven highthen low at a high frequency 92. This creates a second periodic linkquality indicator signal indicating that the network link is marginallyoperational because the MSE is higher than the SNR threshold value.

FIG. 2 is a block diagram depicting a embodiment of a quality indicatoremploying a Light Emitting Diode (LED) to generate a visual qualityindicator according to the present invention. A quality indicator LED200 is operably coupled to a previously described link quality indicatorsignal 40 and a voltage source 202. The link quality indicator signal isdriven low and the LED is energized as soon as auto-negotiation iscomplete and the local network chip 10 is attempting to establish anetwork channel 32 (FIG. 1). After a network channel is established, thequality indicator LED will remain energized while the network channel isoperating reliably with a good SNR.

The link quality indicator signal will be driven high and the qualityindicator LED will no longer be energized when the local network chipreceive error signal indicates a problem with the communication channeland the local network chip is unable to receive packet data. The qualityindicator LED will blink with a varying frequency to indicateintermediate levels of reliability of the network channel.

The following table summarizes the operation of the quality indicatorLED:

LINK QUALITY QUALITY INDICATOR LED STATUS Auto-negotiation in progressOFF Auto-negotiation complete, ON establishing network channel Networkchannel established, ON high SNR Low SNR -close to data error Fast blinkReceive bit errors detected Slow blink Local receiver failure OFF

FIG. 3 is a process flow diagram of quality indicator process of anembodiment of a performance indicator according to the presentinvention. A quality indicator logic module 60 (FIG. 1) includes anencoded quality indicator process 62 for receiving a plurality ofnetwork channel status signals 53 (FIG. 1) transmitted by a localtransceiver 50 (FIG. 1) and processing the plurality of received networkchannel status signals to produce a single link quality indicator signal40 (FIG. 2) used to drive a link quality indicator LED 200 (FIG. 2).

At reset 300, the quality indicator process turns a link qualityindicator LED 200 (FIG. 2) off 302. The quality indicator process checksa auto-negotiation complete status signal 74 (FIG. 1) and loops back toreset the link quality indicator LED to off if the auto-negotiationcomplete signal indicates that the auto-negotiation process has not beencompleted.

If the auto-negotiation complete status signal indicates that theauto-negotiation process is complete, then the quality indicator processturns the link quality indicator LED on 308.

The quality indicator process checks 310 a link status signal 76(FIG. 1) and returns to check the auto-negotiation complete statussignal 304 if the link status signal indicates that the communicationchannel is no longer established. If the auto-negotiation completestatus signal indicates that the auto-negotiation process is notcomplete, the quality indicator process turns the link quality indicatorLED off 302 and continues monitoring the auto-negotiation completestatus signal as previously described waiting for the auto-negotiationcomplete status signal to indicate that the auto-negotiation process iscomplete.

If the quality indicator process confirms that the communication channelis open 310, the quality indicator process checks to see of a localreceiver status 80 (FIG. 1) indicates that data can no longer be sentreliably over the network channel. If data can no longer be sentreliably over the network channel, the quality indicator process turnsthe link quality indicator LED off 314 and returns to monitoring thelink status signal 310 as previously described.

If local receive status signal indicates that data is being reliablysent over the network channel, the quality indicator process turns thelink quality indicator LED on 316 and checks a receive error statussignal 84 (FIG. 1) to confirm that there are no framing or receivecoding errors as provided for in the IEEE 802.3 networking standard.

If the receive error status signal indicates that there are no framingor receive coding errors, the quality indicator process turns the linkquality indicator LED off for a first period of time 320 and then backon 322 for the first period of time. The quality indicator processcontinues processing by returning to checking the link status signal310.

In one embodiment of a quality indicator process according to thepresent invention, the link quality indicator LED is turned OFF for aperiod of 80 msec and back on for a period of 80 msec in order to causethe link quality indicator LED to blink at a low frequency if theauto-negotiation is complete and the network link is established butthere are framing or receive coding errors.

In another embodiment of a quality indicator process according to thepresent invention, the on and off periods of the LED are differentcreating a periodic signal with asymmetric on and off periods.

If the receive error signal indicates that there are no framing orreceive coding errors as provided for in the IEEE 802.3 networkingstandard, the quality indicator process checks a previously describedMSE signal 82 (FIG. 1) by comparing 324 the MSE signal to a previouslydescribed SNR threshold signal 78 (FIG. 1). If the MSE signal is lessthan or equal to the SNR threshold signal, the quality indicator processcontinues processing by checking 310 the link status signal aspreviously described.

If the MSE signal is greater than the SNR threshold signal, the qualityindicator process turns the link quality indicator LED off for a secondperiod of time 326 and then back on 327 for the same period of time. Thequality indicator process continues processing by returning to checkingthe link status signal 310.

In one embodiment of a quality indicator process according to thepresent invention, the link quality indicator LED is turned OFF for aperiod of 3 msec and back on for a period of 3 msec in order to causethe link quality indicator LED to blink at a high frequency.

In another embodiment of a quality indicator process according to thepresent invention, the on and off periods of the LED are differentcreating a periodic signal with asymmetric on and off periods.

Although this invention has been described in certain specificembodiments, many additional modifications and variations would beapparent to those skilled in the art. It is therefore to be understoodthat this invention may be practiced otherwise than as specificallydescribed. Thus, the present embodiments of the invention should beconsidered in all respects as illustrative and not restrictive, thescope of the invention to be determined by claims supported by thisapplication and the claim's equivalents rather than the foregoingdescription.

What is claimed is:
 1. A method for providing a channel quality indicator for a communication system, the method comprising: receiving a communication signal via a network channel; measuring a status value based on the communication signal, wherein the status value is associated with the network channel; generating a channel quality indicator based on the status value; generating a reporting signal based on the communication signal; and transmitting the channel quality indicator as part of the reporting signal.
 2. The method of claim 1, wherein the status value is based on a signal to noise ratio of the communication signal.
 3. The method of claim 2, wherein the signal to noise ratio of the communication signal is compared to a threshold.
 4. The method of claim 1, wherein the status value is based on a mean squared error of the communication signal.
 5. The method of claim 1, wherein the status value is based on a bit error rate of the communication signal.
 6. The method of claim 1, further comprising encoding the channel quality indicator.
 7. A system for providing a channel quality indicator for a communication system, the system comprising: a processor operable to: receive a communication signal via a network channel; measure a status value based on the communication signal, wherein the status value is associated with the network channel; generate a channel quality indicator based on the status value; generate a reporting signal based on the communication signal; and transmit the channel quality indicator as part of the reporting signal.
 8. The system of claim 7, wherein the status value is based on a signal to noise ratio of the communication signal.
 9. The system of claim 8, wherein the processor is operable to compare the signal to noise ratio of the communication signal to a threshold.
 10. The system of claim 7, wherein the status value is based on a mean squared error of the communication signal.
 11. The system of claim 7, wherein the status value is based on a bit error rate of the communication signal.
 12. The system of claim 7, wherein the processor is operable to encode the channel quality indicator.
 13. A system for providing a channel quality indicator for a communication system, the system comprising: a receiver operable to receive a communication signal via a network channel; one or more processors operable to generate a channel quality indicator based on a status value measured from the communication signal; and a transmitter operable to report the channel quality indicator periodically and aperiodically, wherein a frequency of the report is selectable based the communication signal.
 14. The system of claim 13, wherein the status value is based on a signal to noise ratio of the communication signal.
 15. The system of claim 14, wherein the one or more processors are operable to compare the signal to noise ratio of the communication signal to a threshold.
 16. The system of claim 13, wherein the status value is based on a mean squared error of the communication signal.
 17. The system of claim 13, wherein the status value is based on a bit error rate of the communication signal.
 18. The system of claim 13, wherein the one or more processors are operable to encode the channel quality indicator. 